Polymerization of olefins in the presence of a ziegler type catalyst plus a surfactant



United States Patent PGLYIVTERIZATIGN 0F @LEFINS IN THE PRES- ENCE (W AZIEGLER TYPE CATALYSTPLUS A SWFACTANT Lloyd E. Weeks, reve Coeur, andRobert 3. Mcliianirnie,

Glendale, Mo assignors to Monsanto Company, a corporation of Delaware NoDrawing. Griginal appiication Dec. 19, N57, Ser. No. 703,766, new PatentNo. 3,6tl,132, dated (Bet. 23, E62. Divided and this application Mar.26, 1962, Ser. No. 182,562

6 Claims. (Cl. Mit -$45) This invention relates to the use of Zieglercatalysts to effect chemical reactions, especially polymerizations. Incertain preferred aspects the invention pertains to the production ofhigh-density polyethylene by polymerizing ethylene in the presence of acatalyst exemplified by the material obtained by the interaction of atrialkylaluminum with titanium tetrachloride, said catalyst having beenes- "pecially treated to ameliorate the effects of aging of saidcatalyst.

' STORAGE OF ZIEGLER CATALYSTS Ziegler catalysts, for whatever usedesired, can be prepared in the vessel in which the catalyzed reactionis to be carried out, or can be prepared in one vessel and thentransferred to the intended reaction vessel, and in either event caneither be used immediately after preparation, or after a period of timeelapses between the preparation of the catalyst'and its subsequent useto catalyze, e.g., polymerization. There are certain practicaladvantages in preparing a considerable quantity of a Ziegler catalystand then storing same and using the stored catalyst as a stock fromwhich to draw portions thereof for use in a series of batch reactions orover an extended period of time in a continuous reaction. Not only isthe number of catalyst preparations minimized, but uniformity in theratio of the materials going into making the Ziegler catalyst is thusassured. Further, in efiecting Ziegler polymerizations, it has beenfound that preparation of the catalyst in the vessel in which thepolymerization is to be conducted tends to 'result in'more severeplanting of polymer on the surfaces of the reaction vessel, heatexchange surfaces within the vessel, stirrers and the like, than occurswhen the catalyst is first prepared in a separate vessel and then aportion or all of the catalyst is transferred into the polymerizationvessel for use.

However, Ziegler catalysts on standing, i.e., during storage, tend toundergo certain changes, the nature of which is not well understood, butwhich result in various disadvantages. Possibly the most undesirableeffect of storing or aging Ziegler catalysts is loss of catalyticactivity. Thus, Ziegler catalyst allowed to stand at room temperaturefor one day prior to its use is found to have a significantly loweractivity, as measured, for instance, by the weight of monomer, e.g.,ethylene, whose polymerization can be eifected by a given weight of thecatalyst in a given period of time, than the same catalyst if usedimmediately after preparation. The loss in catalyst activity continuesto be more severe it the storage period is extended. The lessenedactivity is noted not only in polymerizations but also in otherreactions catalyzed by Ziegler catalysts.

Another important eifect of aging Ziegler polymerization catalysts isthat the longer the aging period, the higher the molecular weight of theresulting polymer, as reflected 3,159,615 Patented Dec. 1, 1964 "iceSUMMARY OF INVENTION The essence of the present invention lies in theuse of nonionic surfactants to prevent or overcove the loss of activitythat normally occurs on aging, i.e., storage, of Ziegler catalysts. Inone embodiment of the invention, a nonionic surfactant is added to afresh Ziegler catalyst, i.e., is added to a Ziegler catalyst immediatelyafter or very shortly after its preparation; after a period of storagethe thus-treated catalystis more active than it would have been had thesurfactant not been added and the catalyst stored under the sameconditions for the same time. Thus, the aged catalyst has been enhancedin activity by practice of the invention. In another embodiment, Zieglercatalyst that has been stored for such times and under such conditionsthat it is of less activity than when fresh is enhanced in activity byadding thereto a nonionic surfactant. The uses of nonionic surfactantalso make it possible to obtain the desired lower molecular weight rangeof polymers over longer periods of time and with older catalysts thancould otherwise be employed for this purpose.

The invention is not dependent on any particular theory that might beadvanced to explain these phenomena. It may be noted that both cationicand anionic surfactants have been tried but found incapable of obtainingthese results; the invention is of general application to nonionicsurfactants. Furthermore, addition of the nonionic surfactant to eitherof the components, for example, trialkylaluminum or TiCl used inpreparing Ziegler catalyst, is inetfectiverather, the surfactant must beadded to the catalyst after it has been prepared.

ZIEGLER-TYPE CATALYSTS There has recently come into commercialprominence the polymerization of ethylene and other monomers through theagency of a type of catalyst advanced by Prof. Dr. Karl Ziegler of theMax Planck Institute at Mulheim, Ruhr, Germany. In general, Zieglercatalysts can be obtained by treating a salt or oxide of a metal ofGroup IV-B, V-B, VIB, VII or VIII, with a metal of Group I, II or III inmetallic, hydride, or organornetallic form. Naturally, the production ofan active catalyst will be considerably dependent on the choice of thesecomponents, their proportions, and the manner in which they may becombined. Probably the preferred group of these catalysts is thatdisclosed in Belgian Patent No. 533,362, issued May 16, 1955, toZiegler, the disclosure of which is hereby incorporated herein byreference, namely cata- Belgian Patent No. 533,3 62, in various ways,for example, as follows. Instead of or in addition to the aluminumtrialkyls, catalysts of the type described in the Belgian patent can bemade by reacting the various metal compounds of Groups IV-B, V-B andVI-B disclosed therein with aluminum compounds of the general formula,RAlXg; where R is hydrogen or hydrocarbon, X means any other substituentincluding hydrogen or hydrocarbon, particularly dialkyl or diarylaluminum monohalides, also aluminum hydride, alkyl or aryl aluminumdihydrides, dialkyl or diaryl aluminum hydrides, alkyl or aryl aluminumdihalides, alkyl or aryl aluminum dialkoxy or diaryloxy compounds,dialkyl or diaryl aluminum alkoxy or aryloxy compounds. Similarly,instead of or in addition to the organo-alurninum compounds, organiccompounds of magnesium or zinc can be used, and these can contain eithera single or two hydrocarbon radicals, those of especial interest beingGrignard compounds, magnesium dialkyls, mixed organo zinc compounds suchas C H ZnI and zinc dialkyls, all of these, of course, being reactedwith compounds of Groups IV-B, V-B or VI-B metals. Another Ziegler-typecatalyst is prepared by the interaction of an aluminum compounds of thegeneral formula, R AIX, where R is a hydrocarbon radical such as alkylor aryl, and X is a halogen, such as chlorine or bromine, with acompound of a metal of Group VIII of the Periodic System, e.g., iron,nickel, cobalt, or platinum, or manganese, for example, dimethylaluminummonobromide plus ferric chloride, diisobutylaluminum chloride plusnickel (trivalent) chloride, diethylaluminum monochloride plus maganicchloride. Yet another combination is that of the Group IV-B, V-B or VI-Bmetal compounds with aluminum compounds of the general formula R AlX,Where R is hydrogen or a hydrocarbon radical, and X is the radical of asecondary amine, a secondary acid amide, a mercaptan, a thiophenol, acarboxylic acid, or a sulfonic acid, e.g., piperidyl diethylaluminumplus TiCl dimethylaminodiethylaluminum plus zirconium tetrachloride,ethylmercaptodiethyaluminum plus TiCl Another of the classes ofZiegler-type polymerization catalysts comprises compounds of the GrouplV-B, V-B and VI-B heavy metals as previously mentioned, combined withthe alkali metal alkyls, for example, with lithum-, sodium-, orpotassium methyl, -ethyl, -benzyl, -isobutyl, or with complex compoundsof such alkali metal alkyls with organic compounds of aluminum,magnesium or zinc as mentioned above, or complex compounds of alkalimetal hydrides with such organic compounds of aluminum, magnesium orzinc, for example, butyl lithium plus zirconium tetrachloride, sodiumtetramethylaluminum plus titanium tetrachloride or plus thoriumacetylacetonate, Other Zieglertype catalysts are prepared by using (inconjunction with compounds of Group IV-B, V-B and VLB metals), insteadof trialkylaluminums, triaryl-, triaralkyl, trialkarylor mixed alkylandaryl-aluminum, zinc, magnesium or alkali metals, e.g., phenyl sodiumplus TiCl Those skilled in the art having knowledge of these mattersrefer to catalysts of the foregoing type as Ziegler or Ziegler-typecatalysts; or as Ziegler catalysts adapted for low-pressurepolymerization of ethylene or ethylenically unsaturated monomers; and topolymers prepared by their action as Ziegler or Ziegler-type polymers,the terms Ziegler and Ziegler-type being used synonymously. Zieglercatalysts, of course, are not to be understood as limited to thoseactually described by Professor Ziegler, any more than, for example,Friedel-Crafts catalysts are limited to those described by Friedel andCrafts; rather, the term Ziegler brings to mind a particular type ofcatalytic materials, some of which were earlier, and are currently, andno doubt in the future will be, described by persons other than Zieglerand his associates. While the principal classes of such catalysts havebeen listed, this listing is not to be construed as complete, andvarious other such catalysts than those set forth may also be used toproduce polymers. Thus ethylene and other monomers can be polymerized bycatalysts obtained by treating compounds of heavy metals, especiallycompounds of the Group IV-B, V-B and VI-B metals, not withorganometallic compounds but rather by reducing agents such as: alkalimetals, e.g., lithium, sodium, potassium; alkali hydrides, e.g., lithiumhydride, sodium hydride; complex alkali aluminum and alkali boronhydrides, e.g., lithium aluminum hydride; complexes of alkali metalhydrides with boron triaryls or boric acid esters or boronic acidesters; and especially titanium and zirconium halides reduced by zinc oralkaline earth metals or other earth metals including the rare earths,or hydrides of same; said reductions being effected in the completeabsence of oxygen, moisture, and compounds containing active hydrogenatoms as determined by the Zerewitinoff method. Attention is furtherdirected to the teaching of various of the foregoing catalysts inZieglers Belgian Patents 534,792 and 534,888, the disclosure of whichare hereby incorporated herein by reference. Still another disclosureincorporated herein by reference is that of Belgian Patent 538,782,issued jointly to Montecatini Societa Generale per Llndustria MinerariaE. Chimica Anonima and Prof. Dr. Karl Ziegler, disclosing thepolymerization of olefins having at least 3 carbon atoms in themolecule, and their copolymerization with each other and with ethylene,using a variety of Ziegler catalysts; olefins, especially Ot-OlCfinS,disclosed in said Belgian Patent 538,782 include propylene, butylene,isobutylene, pentylene, hexylene, vinyl cyclohexene and styrene.Substantially, the same disclosure is found in Australian patentapplication 9651/55 also filed by Montecatini and Ziegler jointly.Catalysts of the said Belgian Patent 538,782 and Australian application9651/55 are obtained by reaction of compounds of metals of the left-handcolumn of the 4th to 6th groups of the periodic table of elements,including the thorium and uranium groups, with metals, alloys, metalhydrides, or metal-organic compounds of metals of the 1st to 3rd groupsof the periodic table. Yet another disclosure incorporated herein byreference is that of Zieglers Australian patent application 13,453/55,opened to public inspection May 10, 1956 directed to polymerizingethylene with catalysts comprising mixture of organic compounds of themetals of Groups I to III of the Periodic System of the general formulaR MeX, wherein R represents a hydrocarbon radical; X, a hydrocarbonradical or halogen; Me, a metal of Groups I to III of the PeriodicSystem; and n, an integer which is less by one than the valency of themetal Me, with compounds of the metals of Group VIII of the PeriodicSystem or of manganese.

A portion of the Ziegler catalysts can be defined as catalystscomprising mixtures of metals or metal compounds of the 1st to 3rdgroups of the periodic chart of the elements with compounds of metals ofthe 4th to 6th side groups (including thorium and uranium) of the saidperiodic chart.

Another group of valuable Ziegler catalysts can be defined as mixturesof organic compounds of metals selected from the group consisting of RMeX in which R is bydrocarbon, Me is a 1st to 3rd group metal, X ishydrogen, hydrocarbon or halogen, and n is a number which is lower by 1than the valence of the metal Me, with a salt of a group IV-B to VI-Bmetal. The molar proportion of the organic metal compound is ordinarilysufiieient to reduce the valence of the group IV-B to VI-B metal atleast in part.

Ziegler catalysts can also be defined as inciuding all polyvalent metalcompounds in combination with reducing agents, particularlyorganometals, which are effective to reduce the valence of thepolyvalent metal or as compositions containing polyvalent metals in avalence state lower than their maximum state and adapted for thelowpressure polymerization of ethylene so that when suspended in aconcentration of about 20 mmoles/liter (based on polyvalent metal) in awell-agitated inert solvent, it will cause an ethylene uptake rate of atleast 5 grams per hour per liter of solvent.

It will be seen from the foregoing that a large variety of materials canbe employed in the formation of a Ziegler catalyst. It is generallyconsidered that the Ziegler catalysts are best obtained by interactionof a polyvalent metal compound with another metal in elemental orcombined form resulting in reduction of the valence state of the firstsaid metal. The polymetal Ziegler catalyst is believed to act as aheterogeneous catalyst, i.e., at least some of the product obtained bythe interaction of the materials in question is present in solid formalthough often in such finely divided form as to be of colloidal orsub-colloidal particle size. The Ziegler catalyst can be employed in theabsence of any extraneous liquid suspending agent, such as a liquidinert hydrocarbon, e.g., kerosene, but is more often employed in theform of a colloidal solution or suspension in such a liquid.

The essence of the present invention, however, is not to be found in theparticular Ziegler-type catalyst employed but rather in the treatment ofsuch catalyst with a nonionic surfactant with consequent advantages whenused to catalyze a variety of chemical reactions, polymerization ofethylenically unsaturated monomers being of particular interest.

ZIEGLER REACTIONS AND POLYMERS Ziegler catalysts can be employed tocatalyze a variety of chemical reactions, for example, the chlorinationof benzene to'produce monoand polychlorobenzenes, especially orthoandpara-dichlorobenzene. of most intense commercial interest at the presenttime is polymerization. The present invention is broadly applicable toall Ziegler catalyst, and their use in all chemical reactions catalyzedthereby, and, insofar as polymerization is concerned, is broadlyapplicable to all Ziegler-type polymers, i.e., all polymers prepared bypolymerizing a monomer or mixture of monomers in the presence of aZiegler-type catalyst. A monomer which can be so polymerized canproperly be called a Ziegler-polymerizable monomer. Of especialinterest, of course, are those Ziegler solid polymers of sufficientlyhigh molecular weight to be useful in the plasticsindustry, but benefitsof the invention are obtainable in preparing lower molecular weightZiegler semi-solid and even liquid polymers which can be used, forexample, in adhesives, as lube oil additives, etc. The preferredpolymers have a molecular weight of at least 2,000 and preferably10,000. Those Ziegler polymers to which the preparation of the presentinvention is applied with particular advantage generally have muchhigher molecular Weights ranging from 20,000 to 50,000 or 100,000 andeven, in many cases, as high as 1,000,000 to 3,000,000 or more. Themolecular weights in question are those calculated in the conventionalmanner on the basis of the viscosity of the polymer in solution asdescribed in the Journal fiir Praktische Chernie, 2nd Series, vol. 158,page 136 (1941) and the Journal of the American Chemical Society, 73,page 1901 (1951).

At the present time, ethylene is the preferred monomer for preparingZiegler polymers. The ethylene can be homopolymerized, or can becopolymerized with varying amounts, particularly on the order of from 2to percent, of higher olefins such as propylene, or butylene, especiallythe former. The ethylene can also be copolymerized with butadiene and/or isoprene as disclosed in the copending application of Carroll A.Hochwalt, Serial No. 502,008, filed April 18, 1955. Also of interest arethe copolymers of butadiene and/ or isoprene with styrene, disclosed inthe copending application of Carroll A. Hochwalt, Serial No. 501,795,filed April 18, 1955. Homopolymers of butadiene, homopolymers ofisoprene, and copolymers of butadiene with isoprene, as prepared by theuse of Ziegler-type catalysts are also of great interest, havingexceptionally low temperature properties, as disclosed in the copendingapplicaton of Robert J. Slocombe,

6 Serial No. 502,189, filed April 18, 1955. Other ethylenicallyunsaturated hydrocarbons whose Ziegler polymers are of potentialinterest include propylene, butylenes, especially butene-l, amylenes andthe like. Substituted olefins are also of interest, such asvinylcyclohexene, styrene,

vinylnaphthalene, vinyl aromatic hydrocarbons generally The reactionetc. Styrene when polymerized in the presence of Zieglertype catalystsgives a high molecular weight polymer showing a crystalline structure byX-ray diffraction examination. Ziegler-type polyvinyl ethers, especiallythe homopolymers of alkyl vinyl ethers, e.g., ethyl vinyl ether, 2-ethylhexyl vinyl ether, etc., and copolymers of same with ethylene andother copolymerizable ethylenically unsaturated comonomers can also beprepared by the action of Ziegler catalysts, as disclosed in thecopending application of Earl W. Gluesenkamp, Serial No. 507,717, filedMay 11, 1955. A variety of copolymers of the various monomers namedabove with each other and with other comonomers can be prepared byZiegler catalysis, and the present invention in its broadest scopeincludes all such and, in fact, all polymers prepared through the agencyof Ziegler-type catalysts on any single monomer or mixture of monomerspolymerizable with such catalysts.

Despite the broad scope of the invention, it will be found moreconvenient in most of the present application to discuss the inventionwith specific reference to preferred embodiments thereof, and,accordingly, Zieglertype polyethylene will be especially referred to byway of example. Likewise referred to especially by way of example willbe catalysts prepared by the interaction of a trialkylaluminum withtitanium tetrachloride, this being the preferred example of thepreferred group of Ziegler catalysts which are those prepared byinteraction of (a) an aluminum compound of the general formula RgAlXwherein R is an alkyl, cycloalkyl or aryl radical and X .is hydrogen,halogen, or an alkyl, cycloalkylor aryl radi- THE INVENTION IN FURTHERDETAIL In accordance with preferred embodiments of the presentinvention, an active Ziegler catalyst is prepared, usually but notalways as a dispersion in an inert organic liquid; and there is added tosuch catalyst a nonionic organic surfactant in an amount effective toameliorate the effect of aging of the catalyst. A suitable amount ofsurfactant will vary somewhat dependent upon the particular surfactant,catalyst and its age, and the reaction conditions to be employed. Ingeneral, the amount of surfactant is in the neighborhood of from .1 to50 weight percent based on the weight of the catalyst complex, i.e.,from .1 to 50 parts by weight surfactant per 100 parts total materials,e.g., trialkylaluminum plus TiCL, interacted to form the catalyst. It iswell to agitate the catalyst vigorously when adding the surfactantin-order to achieve intimate contact; The treatment with surfactant isvery effectively carried out at room temperature, although elevatedtemperatures, such as up to 90 C., or lowered temperatures, such as downto 70- C. are permissible and are often convenient when the catalyst hasbeen prepared or stored at such temperatures. The Weight percent ofsurfactant on the basis defined above will ordinarily be in the range of0.1 to 5 or 10 percent. It will be realized that the weight percent ofsurfactant will usually be a better measure of the modification thanwill the amount of surfactant calculated on a molar basis. However, itcan be said that it will seldom be desirable to use more than 0.3 moleof surfactant per mole of catalyst (based on grammoles of polyvalentmetal compound, e.g., TiCl and that less than about 0.1 mole ofsurfactant permole of catalyst will ordinarily be employed, for example,from 0.001 to 0.1 mole of surfactant per mole of catalyst.

7 THE SURFACTANTS The dispersing agents utilized in the presentinvention to improve the properties of Ziegler-type catalysts arenonionic surfactants. A preferred class of nonionic surfactants for usein the present invention are the polyoxyalkylene compounds, whichcompounds are characterized by the presence in the molecule of one ormore polyoxyalkylene chains, forming the hydrophilic portion, and one ormore high molecular weight hydrocarbon radicals, forming the lipophilicportion. Particularly useful are such compounds containing 12 to 22 ormore carbon atoms in the lipophilic portion of the molecule and at leasttwo polyoxyethylene groups forming the hydrophilic portion. Thepolyoxyethylene portion can be connected to the hydrocarbon portionthrough a carboxyl group (as where the hydrocarbon radical is in a longchain acyl group), an ether linkage (as where the hydrocarbon radical isin the residue of a long chain aliphatic alcohol, or an alkylatedphenol, or where the hydrocarbon radical is attached through a carboxylor ether linkage to the residue of a polyhydroxylic compound which, inturn, is linked through oxygen to the polyoxyethylene chain), an aminelinkage (as where the hydrocarbon radical is in the residue of a longchain amine), an amide linkage (as where the hydrocarbon radical is inthe residue of a long chain fatty acid amide), or a thioether linkage(as where the hydrocarbon radical is in the residue of a long chainmercaptan) A surface active agent might be considered broadly asincluding any material capable of materially influencing interfacialforces between insoluble liquids or liquids and solids; in ordinaryusage and as employed herein, however, the term surfactant is notintended to extend to such materials as bentonite, polyvinyl esters andalcohols, monohydroxylic alcohols, certain alkyd resins, and specialtiessuch as water repellents which are not used industrially to lowersurface tension. The nonionic surfactants are materials which do notreadily ionize in solution and which gain their hydrophilic characterfrom either polyhydroxylic or polyoxyalkylene residues. Some of thepolyoxyalkylene surfactants useful in the present invention can berepresented by the formula:

in which R is a straight or branched alkyl or alkylphenyl group of 6 to22 carbon atoms; X is a number from 2 to to 30 representing the averagenumber of oxyalkylene groups in the surfactant molecules; Y is o R 3I I,and R is H or (Z) H; Z is C l-I 0, C H O or C H O. When Z representsethylene oxide, it is ordinarily preferred that there be about 2 to 20such groups in the surfactant molecule. Examples of nonionic surfactantsthat are effective in modifying Ziegler catalyst are: Sharples nonionicNo. 2l8a polyethylene glycol tertiary dodecyl thioether containing anaverage of about 11 oxyethylene groups per molecule, Ipepal CA-an alkylaryl polyethylene glycol other which is a condensation product of onemole of tertiary octyl phenol with about moles of ethylene glycol,Pluronic L62-polyoxyethylene-polyoxypropyiene condensate, and SteroxCD-a stenol polyoxyethylene ether which is a condensation product oftall oil and about 9 molar equivalents of ethylene oxide. Of course, thenumber of applicable nonionic surfactants is very large, and it is notpractical to give examples of all of them here. However, the nonionicsurfactants can be designated by use of the Hydrophile-Lipophile Balancemethod, abbreviated HLB. The HLB value is a function of the weightpercentage of the hydrophilic portion of the molecule of a nonionicsurfactant.

The HLB values for many nonionic surfactants may be calculated by use ofthe formulas (William C. GriIfin, Journal of the So ciety of CosmeticChemists, vol. V, No. 4, December,

0 (1 or HLB= g age of polyhydric alcohol content.

In general, the nonionic surfactants utilized herein will have HLBvalues about 20. A few such surfactants, togather with their HLB values,are set forth below by way from about 2 to Or example:

Trade Name Chemical Designation HLB Atlas G-l706 Polyoxycthylenesorbital beeswax 2 derivative. Span G5 Sorbiten tristearatm 2.1 Atmul67. Glycerol monostearatm 3. 8 Span 8O Sorbitan lvfonooleateu 4. 3Erncol PL50 Propylene glycol fatty acid ester- 4. 5 Atlas 6-2124.Diethyleneglyeol monolaurate .1 6.1 Atlas 01-2242." Polyoxyethylenedioleate .1 7. 5 Tween 61 Polyoxyethylene sor'eitan monostea- 9. 0

r ve. Atlas G-3763. Polyoxyethylene fatty amine 10 Atlas G3705Polyoxyethylene lauryl other 10. 8 Atlas G-2116. Polyoxyethyleneoxypropylene oleate. ll Igepal CA-630 Polyoxyethylcne alkyl phenol 12. 8Fmulphor EL7l9 Polyoxyethyleno vegetable oil 13.3 Atlas (R -3720Polyoxyethylene stearyl alcohol 15.3 Tween 40 Polyoxyethylene sorbitaninonopal- 15. 6

mitatc. Brij 35 Polyoxyethylene lauryl other .1 16. 9 Atlas (Ir-2159Iolyoxyethylcne monostearate 18. 8

' Nonionic surfactants having HLB values in the range of about 7 to 15or so are ordinarily very suitable.

A particular group of polyhydric alcohol surfactants which are useful inthe present invention are the ditertiary acetylenic glyools, i.e.,compounds in which both carbon atoms of an acetylene group are attachedto the carbinol carbon atoms of tertiary alcohol moieties; suchsurfactants under the names, Surfynol 82, Surfynol 102, and Surfynol 104vary in molecular weight range from about grams to about 230 grams orso.

It will be understood that the enumeration of certain nonionicsurfactants herein is not intended to exclude other nonionicsurfactants, and that any nonionic surfactants having surfactantproperties of the same type as the herein named nonionic surfactants areuseful and contemplated as within the present invention.

The condensation products of alkylphenols with ethylene oxide constitutea valuable class of nonionic surfactants for use in the presentinvention. Ordinarily, such compounds will contain 5 to 10 or 15 molesethylene oxide per mole of alkylphenol, and the alkyl group will usuallycontain 5 to 15 or so carbon atoms. This class is exemplified by adodecylphenol-ethylene oxide in which there is an average of about 7.6moles ethylene oxide for each mole of phenol.

It will be realized that the nonionic surfactant dispersing agents ordispersants disclosed herein are entirely different from the inerthydrocarbon solvents or suspending agents which are sometimes referredto as dispersants.

While the present invention is not to be limited by any particulartheory of its mechanism, it is believed that the nonionic surfactantsaid in keeping the catalyst particles dispersed or separated, therebyimproving the activity of the catalyst.

The surfactant-modified Ziegler catalysts contemplated herein are, ofcourse, active Ziegler catalysts. Ziegler catalysts which have had theiractivity destroyed, as by addition of Water, for example, or which areotherwise completely deactivated, even after addition of nonionicsurfactant, are not contemplated as within the present surfactant.

causing an ethylene uptake rate of at least 1 gram per hour per liter ofreactor space at atmospheres pressure; it is not usually practical touse a catalyst which does not have an uptake rate of at least 10. grams/hour/ liter under such circumstances, and it is preferable that theuptake rate be 100 grams/hour/ liter orhigher.

We ordinarily prefer to prepare an active Ziegler catalyst as adispersion in an inert organic liquid, such as an aliphatic or aromatichydrocarbon as will be discussed more in detail hereinafter. Thisdispersion is ordinarily a colloidal suspension of catalyst particles inthe liquid.

'We then add the chosen nonionic surfactant in the chosen amount, andpreferablythe surfactant before addition is dissolved or dispersed in aninert organic liquid and the addition made'with vigorous agitation so asto prevent localized concentration of surfactant during the treatment ofthe catalyst therewith. It is necessary to prepare an active Zieglercatalyst first, and then to treat same with the chosen surfactant.Ordinarily, the monomer is polymerized in the presence of the catalystdispersion which has been treated with the surfactant. However, prior to'the polymerization or other'use of the catalyst, part or all of thesolvent may be removed as by filtration, evaporation, and the like, carebeing taken not to use conditions for such a separation that willdeactivate the catalyst. It is also possible if a dry catalyst, orcatalyst in a reduced 'amount of organic liquid, is to be used, toprepare the active catalyst in such form prior to its treatment with Insuch event, particular care must be taken to insure thorough admixtureof the chosen amount of surfactant with the total catalyst, and this caninvolve using a limited amount of inert organic liquid as a solventand/or suspending agent for the chosen surfactant, or thorough grindingas by ball milling the catalyst, either in a dry condition or with someinert organic liquid present, with the chosen surfactant.

Ordinarily, it is quite sufiicient and, in fact, desirable to use only asingle surfactant. However, it is not outside the scope of the inventionto utilize an admixture of two or more surfactants or an admixture ofany one or more with any other catalyst modifying agent that may bedesired.

DETAILS OF PREPARATION AND USE OF ZIEGLER CATALYSTS More detailedinformation will now be given on preferred Ziegler catalyst and; theirpreparation, and it will be understood that the procedures given abovewith respect to use of nonionic surfactants will be followed. We prefercatalysts prepared by the'interaction of (a) an aluminum compound of thegeneral formula, RgAlX wherein R is an alkyl, cycloalkyl or aryl radicaland X is hydrogen, halogen, or an alkyl, cycloalkyl oraryl radical, with(b) a metal halide selected from the group consisting of the chlorides,bromides and iodides of titanium and zirconium. The preparation ofpolymers will be described, by way of example, with particular referenceto catalysts prepared by the interaction of trialkylaluminums, e.g.,triethylaluminum, triisobutylaluminum, trioctylaluminum, with titaniumtetrachloride.

Suitable aluminum compounds to be reacted with the chlorides, bromidesand iodides/of titanium or zirconium .are those represented by thegeneral formula, R AlX,

wherein R is an alkyl, cycloalkyl or 'aryl radical and X is hydrogen,halogen, oran talkyl, cycloalkyl or aryl radical. By way of example, butnot limitation the following compounds are mentioned:

Triethyl aluminum Triisobutylaluminum Trioctylaluminum 19Didodecyloctylaluminum Diisobutylaluminum hydride TridodecylaluminumDiphenylaluminum bromide DipropylcyclohexylaluminumDitolylmethylaluminum Tri- ,B-phenylethyl) aluminum Diethylaluminumchloride Diisobutylaluminum chloride Diisobutylaluminum iodideDi-(fl-cyclohexylpropyl)isobutylaluminum It is to be understood thatmixtures of the foregoing types of aluminum compounds can be employed.One can use the total reaction mixtures obtained in the formation ofsuch compounds, e.g., by treatment of metallic aluminum with alkylhalides resulting in the formation of such mixtures as R AlCl plus RAlCltermed alkylaluminum sesquihalides.

The aluminum compounds in question are interacted with one or morechlorides, bromides, or iodides of titanium or of zirconium, thechlorides and iodidesbeing preferred. The titanium or zirconium in thesehalides should be in a valence form higher than the lowest possiblevalence. The tetrahalides are especially preferred, although thedihalides, trihalides, mixtures of di-, tri-, and tetrahalides, etc.,can be used. Preferred titanium or zirconium compounds are those thatare soluble in an organic solvent (preferably a hydrocarbon such ashexane, benzene, kerosene, etc.) that is used in preparing the catalyst.T itanium or zirconium compounds other than the named halides, e.g.,those called alcoholates, alltoxides or esters by various investigatorssuch as titanium tetramethoxide (also called tetramethyl titanate),titanium triethoxide, tripropoxytitanium chloride, zirconiumtetra-n-butoxide, or fluonides of titanium or zirconium, or complexessuch as zirconium acetylacetone, K TiF or salts of organic acids such asthe acetates, benzoates, etc, of titanium and zirconium, can be used toprepare catalysts with at least some activity and to that extent can beconsidered equivalents of the halides; however, such compounds areusually prepared from the halides and, hence, are more costly and alsoare usually less active; so their use is economically sound only whereina particular situation favorable effects can be obtained such asincreased solubility in an organic solvent that is used in preparing thecatalyst, or polymer of increased molecular weight, or faster reactionrate. Although the exact action resulting from contacting the aluminumcompound with the titanium or zirconium compound is not understood, itis believed likely that the zirconium or titanium halide is reduced invalence by the reaction of the added aluminum compound. The

-mole ratio of aluminum compound to titanium (or zir conium) compound,or stated another and simpler way, the mole ratio of aluminum totitanium (or zirconium), can vary over a wide range, suitable valuesbeing from 0.1:1 to 10:1 on up to 15:1 or higher. It is generallypreferred to use an Al2Ti mole ratio between 0.3:1 and 5:1. The sameratios apply in the case of the zirconium compounds.

While active catalysts can be prepared by a variety of procedures, thesimplest and perhaps most eifective is to add the titanium or zirconiumhalide to the aluminum compound, or vice versa preferably in thepresence of an inert organic solvent. Such solvents can suitably besaturated aliphatic and alicyclic, and aromatic, hydrocarbons,halogenated hydrocarbons, and saturated ethers. The hydrocarbon solventsare generally preferred. By way of example can be mentioned liquefiedpropane, isobutane, normal butane, n-hexane, the various isomerichexanes, n-heptane, cyclohexane, methylcyclopentane,dimethylcyclohex-ane, dodecane, industrial solvents composed ofsaturated and/or aromatic hydrocarbons, such as kercsenes, naphthas,etc, especially when hydrogenated to remove any olefin compounds andother impurill ties, and especially those ranging in boiling point up to600 F. Also, benzene, toluene, ethylbenzene, any of the xylenes, cumene,decalin, ethylene dichloride, chlorobenzene, diethyl ether,o-dichlorobenzene, dibutyl ether, tctrahydrofuran, dioxane. In someinstances, it is also advantageous to prepare the catalyst in thepresence of a monomer, e.g., liquid ethylene.

It may also be mentioned here that the polymerization can readily beelfected in the presence of any of the classes of solvents and specifiicsolvents just named. If the proportion of such solvent is kept low inthe reaction mixture, such as from to 0.5 part by weight inert organicsolvent (i.e., inert to the reactants and catalysts under the conditionsemployed), per 1 part by weight total polymer produced, solvent recoverysteps are obviated or minimized with consequent advantage. It is oftenhelpful in obtaining efficient contact between monomers and catalystsand in aiding removal of heat of reaction, to employ larger amounts ofsolvent, for example, from to parts by weight solvent per 1 part byweight total polymer produced. These inert solvents, which are solventsfor the monomers, some of the catalyst components, and some of thepolymers, but are nonsolvents for many of the polymers, e.g.,polyethylene, can also properly be termed inert liquid diiuents, orinert organic liquids.

The amount of catalyst required is dependent on the other variables ofthe particular reaction, such as polymerization, and although amounts assmall as 0.01 weight percent based on total weight of monomers chargedare sometimes permissible, it is usually desirable to use somewhatlarger amounts, such as from 0.1 up to 2 to 5 percent or evenconsiderably higher, say up to 20 percent, depending upon the monomer ormonomers, the presence or absence of solvent, the temperatures,pressures, and other reaction conditions. When polymerization iseffected in the presence of a solvent, the catalyst to solvent weightratio should usually be at least about 0.001:1, and much lower values,such as 00001:]. can sometimes be used.

The polymerization can be effected over a wide range of temperatures,again the particular preferred temperature being chosen in accordancewith the monomer, pressure, particular catalyst and other reactionvariables. For many monomers from room temperature down to say 40 C. andeven lower are suitable, and in many cases, it is preferred that thetemperature be maintained at below about C. However, for other monomers,particularly ethylene, higher temperatures appear to be optimum, sayfrom 50 to 75 C. for ethylene. Temperatures ranging up to 100 C. andhigher are generally satisfactory for Ziegler-type polymerization.

The pressure at which the polymerization is carried out is independentupon the chosen monomer or monomers, as well as other variables. In mostinstances, the polymerization is suitably carried out at atmosphericpressure or higher. Although sub-atmospheric pressures are permissible,there would seldom be any advantage. Pressures ranging from atmosphericup to several hundred or even many thousand pounds per square inch,e.g., 50,000 p.s.i. and higher, are suitable. While high pressures arenot required in order to obtain the reaction, they will have a desirableeffect on reaction rate and in some instances on polymer quality. Thechoice of whether or not to use an appreciably elevated pressure will beone of economic and practical considerations taking into account theadvantages that can be obtained thereby.

The catalyst is sensitive to various poisons, among which may bementioned oxygen, water, carbon dioxide, carbon monoxide, acetyleniccompounds such as acetylene, vinylacetylene, alcohols, esters, ketones,aldehydes, and the like, although the extent to which a given quantitywill inhibit catalyst activity will be greatly de endent on theparticular material. For this reason, suitable precautions should betaken to protect the catalyst and the reaction mixture from suchmaterials. An excess of the aluminum compound, particularly mole ratiosof aluminum to titanium or zirconium in excess of about 4:1, tends togive a certain amount of protection against these poisons. The monomersand diluents or solvents, if used, need not be pure so long as they arereasonably free from poisons. It is well to protect the catalyst duringpreparation, storage, and use by blanketing with an inert gas, e.g.,nitrogen, argon or helium.

The monomer or mixture of monomers is contacted with the catalyst in anyconvenient manner, preferably by bringing the catalyst and monomertogether with intimate agitation provided by suitable stirring or othermeans. The agitation can be continued during the polymerization, or insome instances the polymerization mixture can be allowed to remainquiescent while the polymerization takes place. In the case of the morerapid reactions with the more active catalyst, means can be provided forrefluxing monomer and solvent if any of the latter is present, and thusremove the heat of reaction. In any event adequate means should beprovided for dissipating the exothermic heat of polymerization. Ifdesired, the monomer can be brought in vapor phase into contact with thesolid catalyst, in the presence or absence of liquid solvent. Thepolymerization can be effected in the batch manner, or in a continuousmanner, such as, for example, by passing the reaction mixture through anelongated reaction tube which is contacted externally with suitablecooling medium to maintain desired reaction temperature, or by passingthe reaction mixture through an equilibrium overflow reactor, or aseries of the same.

The polymer will be recovered from the total reaction mixture by a widevariety of procedures, chosen in accordance with the properties of theparticular polymer, the presence or absence of solvent, and the like. Itis generally quite desirable to remove as much catalyst from the polymeras possible, and this is conveniently done by contacting the totalreaction mixture, or the polymer after separation from solvent, etc.,with methanolic hydrochloric acid, with an aliphatic alcohol such asmethanol, isobutanol, secondary butanol, or by various other procedures.If the polymer is insoluble in the solvent, it can be separatedtherefrom by filtration, centrifuging or other suitable physicalseparation procedure. If the polymer is soluble in the solvent, it isadvantageously precipitated by admixture of the solution with anonsolvent, such nonsolvent usually being an organic liquid misciblewith the solvent but in which the polymer to be recovered is not readilysoluble. Of course, any solvent present can also be separated frompolymer by evaporation of the solvent, care being taken to avoidsubjecting the polymer to too high a temperature in such operation. If ahigh-boiling solvent is used, it is usually desirable to finish anywashing of the polymer with a low-boiling material, such as one of thelower aliphatic alcohols or hexane, pentane, etc., which aids removal ofthe higher boiling materials and permits the maximum removal ofextraneous material during the final polymer drying step. Such step isdesirably effected in a vacuum at moderate temperatures, preferably wellbelow C.

The foregoing principles and procedures can be applied, with suitablemodifications when necessary, to reactions other than polymerizations,effected in the presence of Ziegler catalysts treated with surfactantsin accordance with the present invention.

In order to illustrate some of the various aspects and advantages of theinvention, the following examples are given. Ethylene has been chosen asa representative monomer, triisobutylaluminum has been chosen as arepresentative reducing agent in preparing the catalyst, titaniumtetrachloride has been chosen as a representative polyvalent metalcompound that is reduced in preparing 'density polyethylene atstandardized conditions. 'lar-type'reactor about 3 inches in diameterand 500 ml.

.at the tip of the stirring blade.

'7.6 moles ethylene oxide (per mole of dodecyl phenol) has been chosenas arepresentative nonionic surfactant.

It will, of course, be understood that variations from the particularcatalyst components, reactants, surfactants,

solvents, proportions, temperatures, and the like can be made withoutdeparting from the invention.

EXAMPLES Activity of catalysts was determined by the rate at whichethylene was polymerized to high-molecular-weight, high- A tubu capacitywas used. It was fitted with side arms for addi- .tion of liquids andwithdrawal of. gas, a thermometer well,

and .a paddle-type, hollow-stem, constant-speed .stirrer. Gas was passedthrough an inletflow'meter into the stirrer shaft, and flowed outintojthe reaction'mixture The off-gas was passed through. a spiralcondenser and a'Dry-Ice (solid CO .trap' to an outletiflow meter.

The apparatus was baked dry, assembled, and flushed with lamp-gradenitrogen. Passage of nitrogen was .continued until the reactiontemperature was attained. The calculatedamount of catalyst wastransferred with a pipette to. the reactor, and enough kerosenewasa'dded to bring the volume to 250 ml. The keroseneused in thereaction vessel and in preparation of the'catalyst had been highlypurified by extensive acid Washing and dried by distillation. Stirringwas started and the mixture was heated to 65 C., heating wasdiscontinued and the gas inlet was switched from nitrogen to ethylene.The inlet and. outlet flow meters were read at 1-minute intervals. Thereactor was cooled with air blast as needed to maintain a temperature of65 C. plus or minus 2 C. A standard run time of 12 minutes was usedthroughout.

The ethylene flow was maintained at such a level that an appreciableexcess of ethylene was always passing through the reactor. Thedifference in the flow meter readings was then plotted against time inminutes and the area under the curve was calculated by the method ofcounting squares. The direct relation between the area and the weight ofpolymer had been estabished from a large number of samples that had beenworked up and weighed. Catalyst activity is reported as grams polymerper hour per liter of initial reaction mixture.

Catalyst was prepared as a slurry in kerosene in a 3- neck Morton flaskwell flushed with nitrogen by means of a nitrogen inlet and outlet andequipped with a highspeed stirrer assembly. The apparatus was firstbaked dry and flushed with lamp-grade nitrogen. Most of the kerosene tobe used was then placed in the flask and the requisite quantity oftriisobutylaluminum was added and washed into the flask with additionalkerosene. The requisite quantity of TiCl was then added dropwise over aminute interval. The TiCl addition funnel residue was then washed intothe flask with the final quantity of kerosene. At the chosen time, thesurfactant, which was the condensation product of dodecylphenol with 7.6moles of ethylene oxide, was added dropwise to the vigorously agitatedcatalyst suspension. Catalyst was stored under nitrogen until used. Whencatalyst was to be tested, the catalyst slurry was well mixed and thenby means of a pipette aliquots were transferred under nitrogen into thereactor.

In each instance, the catalyst components were employed in amounts togive an initial concentrated catalyst slurry containing 173 millimolestitanium per liter of kerosene, which when diluted in the polymerizationreactor with additional kerosene gave a concentration of 13.8

millimoles titanium per liter of kerosene. of aluminum to titanium was0.5.

'Catalyst prepared as described above was tested for activity afterstorage at room temperature for various periods of time. Tests were madeon the catalyst without The mole ratio surfactant (control),xand oncatalyst of the same age treated with from 0.12 to 0'.18 g. ofsurfactant (per 250 ml; solution) immediately-prior to thepolymerization. The 250-ml. solutions employed in the tests contained3.45

millimoles catalyst. Results are in Table I.

Table I RESTORATIONOF CATALYST ACTIVITY BY ADDITION OF SURFAGTANT JUSTBEFORE POLYMERIZATION Ethylene Uptake, gJL/hr.

Age of Catalyst Without With Surfactant Surfactant 5 hours 290 293 247314 261' 316 193 291 109 234 Similar tests were made to determine theeflect of adding the surfactantin the same quantities to thecatalystjust 30 minutes after its initial preparation. Results are inTable II.

'Table "'11 MAINTENANCE OF CATALYST ACTIVITY BY ADDITION OF 'SURFACTANTTO FRESH CATALYST *Activity test run for 20 minutes.

That the surfactant ought to be practically anhydrous was shown bycomparison of the extent of catalyst activation obtained with surfactantfrom the same bottle over a period of time. This surfactant(dodecylphenol-7.6 ethylene oxide) is a hygroscopic liquid and obviouslyabsorbed some moisture from the air on each exposure. The data are inTable III.

Table III EFFECT OF MOISTURE IN DISPERSANT ON CATALYST ACTIVATIONPercent observed Bottle openings: Activation 1 Surfactant dried invacuum oven at 70 C. for 18 hours.

There is, of course, the possibility that very slight quantities ofmoisture are harmless, or even beneficial, but it is apparent from theabove that increasing quantities of moisture cause a decrease in theamount of activation to be obtained.

That the surfactant must be added to the prepared catalyst, at leastwhen triisobutylaluminum and TiCl are used to prepare the catalyst, isshown by the results reported in Table IV.

Table IV COMPARISON OF METHODS OF ADDING DISPERSANT CZII-i Uptake,g.ll.[hr. Method 01' Adding Dispersant 4 hr. 43 hr. 5% days A 341 400252 B 293 332 252 C Inactive D Inactive A. Dispersant added to catalystcomplex hour alter preparation.

B. Dispersant added to catalyst complex just prior to run.

0. Dispersaut added to TiCh solution prior to addition to aluminum alkylsolution.

D. Dispersant added to aluminum alkyl solution prior to addition ofT1014 solution.

While the invention has been described with particular reference tovarious preferred embodiments thereof, it will be appreciated thatvariations from the details given herein can be effected withoutdeparting from the invention in its broadest aspects.

This application is a division of application Serial No. 703,766, filedDec. 19, 1957, and now US. Patent No. 3,060,132.

What is claimed is:

1. A method which comprises polymerizing ot-OICfiIlS containing 2 to 8carbon atoms in the presence of a polymerization catalyst adapted forthe low pressure polymerization of ethylenically unsaturated monomerscomprising the reaction product of (a) a metal compound of O the generalformula R MeX wherein Me is a first to third group metal, R is selectedfrom the group consisting of alkyl, cycloalkyl and aryl radicals and Xis selected from the group consisting of hydrogen, halogen, alkyl,cycloalkyl, and aryl radicals and n is a number which is lower 16 by onethan the valence of the metal Me with (b) a salt of a Group IV-B to VI-Bmetal, and a nonionic surfactant having an HLB value within the range of2 to 20.

2. A method which comprises polymerizing ethylene over an aged trialkylaluminum/titanium tetrachloride catalyst treated with 0.1 to 10% byweight of nonionic surfactant which is the product of the condensationof an alkylphenol with from 5 to 15 moles of ethylene oxide per mole ofalkylphenol.

3. A method according to claim 2 wherein said monomer is ethylene.

4. A method according to claim 1 wherein said surfactant is a product ofthe condensation of an alkylphcnol with ethylene oxide.

5. A method which comprises polymerizing an a-olefinic hydrocarbon of upto 8 carbon atoms over a catalyst comprising the reaction product of (a)an aluminum compound of the general formula R AlX, wherein R is selectedfrom the group consisting of alkyl, cycloalkyl and aryl radicals and Xis selected from the group consisting of hydrogen, halogen, alkyl,cycloalkyl, and aryl radicals with (b) a metal halide selected from thegroup consisting of the chlorides, bromides and iodides of titanium andzirconium, in proportions to give an atomic ratio of aluminum to theother metal between 0.321 and 5:1 and 0.1 to 10% by weight of thereaction product of a nonionic surfactant having an HLB value within therange of 2 to 20.

6. A method according to claim 5 in which the surfactant is the productof the condensation of an alkylphenol with from 5 to 10 moles ofethylene oxide per mole of alkylphenol.

No references cited.

gwAItnsting Officer UNITED STATES PATENT OFFICE 7 CERTIFICATE OFCORRECTION Patent No, 3 159 6l5 December l 1964 Lloyd Eo Weeks et alg Itis hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 1, line 42, for "'planting"' read ----"plat,ing" column 2, linell for "overcove" read overcome column 7 line 63 for "Ipepal" readIgepal column 14 Table III, under the heading "Percent observedActivationflfand opposite "Bottle openings: 5" for "-50" read -18 --qSigned and sealed this 6th day of April 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Commissioner of Patents

1. A METHOD WHICH COMPRISES POLYMERIZING A-OLEFINS CONTAINING 2 TO 8CARBON ATOMS IN THE PRESENCE OF A POLYMERIZATION CATALYST ADAPTED FORTHE LOW PRESSURE POLYMERIZATION OF ETHYLENICALLY UNSATURATED MONOMERSCOMPRISING THE REACTION PRODUCT OF (A) A METAL COMPOUND OF THE GENERALFORMULA RNMEX WHEREIN ME IS A FIRST TO THIRD GROUP METAL, R IS SELECTEDFROM THE GROUP CONSISTING OF ALKYL, CYCLOALKYL AND ARYL RADICALS AND XIS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, HALOGEN, ALKYL,CYCLOALKYL, AND ARYL RADICALS AND N IS ANUMBER WHICH IS LOWER BY ONETHAN THE VALENCE OF THE METAL ME WITH (B) A SALT OF A GROUP IV-B TO VI-BMETAL, AND A NONIONIC SURFACTANT HAVING AN HLB VALUE WITHIN THE RANGE OF2 TO 20.